Electric control system



- Pannmq March 14, 1933. A. J SORENSEN 1391,94?

ELECTRIC CONTROL SYSTEM Filed Dec. 17, 19:51 a Sheets-Sheet l Master Emeggnoy 6 4 27 Generator Power ,1 f Lap 891 0109 Amplifizbp Y load 43006212191 INVENTOR. Andrew J. 801 905012.

By 'QRt CZZM H15 ATTORNEY.

March 14, 1933. J SQRENSEN 1,9015%947 I ELECTRIC CONTROL SYSTEM Filed Dec. 17, 1931 3 Sheets-Sheet 2 Genemzap Loud Speaiiep Vems INVENTOR.

JSomzzsvn.

' HIS A TTORNEY.

Patented Mar. 14, 1933 omen stars Parr erricu NDREW :r. soait sEN, or PITTSBURGI-I, PENNSYLVANIA, ASSIGNQR TO THE UNION swrrcn & SIGNAL COMPANY, or swrssvans', PENNSYLVANIA, A coRronA'rro-N or PENNSYLVANIA nnncrarc coN'rRon SYSTEM Application filed December 17, 1931. Serial No. 581,553.

My invention relates to electric control systems, and particularly to electric control systems adaptable to the operation of railway trains.

' I will describe certain forms of apparatus embodying my invention, and will then point out the novel featuresthereof in claims.

In'the accompanying drawings, Figs. 1 and 2, when taken together constitute a diagrammatic View of one form'of apparatus embodying my invention when applied to a railway train for automatic control of the train brakes, as well as for code signaling and telephone communication. Figs. 3 and 4 when taken together constitute a diagrammatic view of a second form of apparatus also embodying my invention applied to a railway train for governing the operation of the train brakes, where the brakes are to be controlled manually from two different locations on the train in accordancewith telephonic messages communicated between the two different locations. The apparatus of Fig. 1 of the f'nst form and also that of Fig. 3 of the second form is to be installed at the location of the supervising operator, which, in this instance is on the locomotive. The apparatus of Fig. 2 of the first form of my invention and that of Fig. 4 of the second 0 form is to be installed at another point on a train remote from the location of the supervisin operator. While thea-pparatus of Figs. 2 and 4 may be located at any point on the train, it will be referred to in thisdescription in both cases as being mounted in thecaboose of a freight train.

' Where the brakes of a train are to be controlled from two different locations of a train it is desirable that communication between the members of the train crew located at the two locations may be established at any and all times in order that the train may be handled safely and smoothly. To this end I propose to combine a telephone communi- J cating system with an automatic brake control system in such a manner that one communicating channel between the two locations will serve for both functions. In the form of my invention disclosed in Figs. 3 and 4, where the brakes are to be manually controlled at each location, I propose to automatlcally exchange between the two locations, under normal operating conditlons,

periodic impulses of current of audible freof the train to the other may take different forms but a preferred form is that described and claimed in the L. O. Grondahl application for Letters Patent, Serial No.450,135, filed May 6, 1930, on electric train signaling system. i

Although I am here disclosing a specific application of my invention, it will be understood that I do notwish to limit myself to brake control systems for railwaytrains. My invention is equally useful to control systems for railway trains wherein the operator of a leading locomotive can issue instructions to the operator of a helper locomotive. As a matter of fact with my invention the operator of the leading locomotive can read- ;ily control the operation of helperlocomotives. My invention is also equally useful to other control systems where apparatus at two remote points are so associated with each other that it is essential that the operators at the two locations may quickly and readily communicate with each other.

- In the following description, like reference characters refer to corresponding parts in all of the views.

In at least one instance, a contact is illustrated at a point remote from the member which operates it (contact 1D operated by valve D in Fig. 2). The relationship between these elements is indicated by the fact 16 engages a contact 11 in the release, running and lap positions and a contact 12 in both service and emergency positions of handle 5. The contact 17 engages a contact 13 in both release and running positions, a contact 14 in the lap position and a contact 15 in the service position of handle 5.

The equipment of Fig. 1 includes a threeposition circuit controlling master switch MS. [This master switch is manually operated to any one of three positions indicated on the drawings by the numerals 1, 2 and 3. The position 1 is the normal position to which the switch returns under the action of 'a'biasing spring not shown when not actually held manually in one of the other two positions. When the switch MS is left in the No. 1 position, automatic control of the train brakes is effected, as will appear as the specification progresses. The No. 2 position is used when it is desired to deliver a telephone message to the caboose and the No. 3 position is used when a telephone message is to be received from the other end of the train. vIt follows, that the locomotive equipment can be shifted to any one of the three conditions, automatic brake control, speech sending or speech receiving at the will of the locomotive operator.

The locomotive is equipped with a mechanically tuned oscillator or coder N. This coder may take any one of manyforms well-known to the art such for example as'that disclosed and claimed in the P. N. Bossart application for Letters Patent, Serial No. 398,342, filed Oct. 9, 1929 on coding apparatus. It will suffice for this description to say that between the poles P1 and P2 of the field structure E of the coder N there is mounted an armature H pivoted at O. V The armature H is biased by a spring not shown to a mid-position in which the contact members 18, 19, 20 and 23'occupy the positions shown by the heavy lines in Fig. 1. A field winding 21 is connected to a battery 22 by a simple circuit that includesits own contact member 18. The energizing of the field winding 21 causes the armature H to rotate in a clockwise direction as indicated by an arrow. After a slight movement of armature H'the contact member 18 is swung to the right to become disengaged from its contact to rupture the circuit to the field winding 21. Armature H will rotate a little farther and then due to its biasing it Will reverse its movement until contact member 18 again engages its contact to reenergize the field Winding 21. During the interval that armature H is being rotated clockwise due to the energizing of the field winding 21, the contact members 19, 20 and 23 are swung to the left to engage left-hand contacts. The inertia of the armature H in its reverse movement will carry it past its normal position far enough to cause its contact members 19, 20 and 23 to swing to the right to engage right-hand contacts. The biasing. and the weight of the armature H are such that it will have a natural period of oscillationof say eighty cycles per minute, although it will be understood that any other frequency may be selected if desired. It follows, that the contact members '19, 20 and 23 are oscillated between the left-hand and right-hand contacts at the rate of eighty times per minute as long as the field winding 21 isv supplied with current. As will shortly appear, time is divided into sending and receiving periods by the contact members 19 and 20 underv the normal position of the switch MS and the release, running and lap positions of the brake valve handle 5.

26 and 27 are inductor coilslocated on the locomotive in inductive relation with the traffic rails 28 and 29, respectively. By means of these inductor coils 26 and 27 energy is transmit-ted to and. received from the traffic rails by the locomotive apparatus, and to this end they are alternately connected to a transmitting circuit and a receiving circuit by the operation of the contact members 19 and 20 of the coder N under the release, running and lap positions of the handle 5, as will shortly appear.

On the locomotive there is provided a generator G adapted tosupply current of audible frequency, such for example as twenty-five hundred cycles per second. The output of the generator G is delivered to a power transmitter PT by a circuit easily traced and which includes the contactor 30 of the master switch .MS in its No. 1 position. The power transmitter PT amplifies the current received from the generator G and delivers it to the coils 26 and 27 through a circuit that includes the right-hand terminal of power transmitter PT, wire 31, contactor 32 of switch MS in itsNo. 1 position, wire 33, left-hand contact of 19, contact 34 of a manually operated signaling switch K, wire 35, contacts 9, 4 and 6, wire 36, coils 26 and 27 in series, wire 37, contacts 7, 16

and 11, wire 38, a second contact 39 of the.

of the handle the output. of the generator G 1s modulated alternately by the'modulators M1 or M2 in the following manner. Suppose the relays 24 and 25 are both deenergized and through back contact of armature as of relay 25, top winding of relay 24,1eft-harid contact of-23 and to the negative terminal C of the source of current. /Vhen contact 23 changes positions to make towards the right, the relay 24- does not at once drop because it is slightly slow-releasing. A circuit now completed from the positive terminal 13 through front Contact of a anature l3, lower Winding of relay 2%, right-hand contact of 23 and to the negative terminal C. Another circuit is also completed, at this time through the front contact of armature 44- of relay 2-l, top Winding of relay 25 and theright-hand contact of 23 to the negative terminal G with 25 the result that relay 25 is picked up. VVh-en contact 23 next swings to the left, the relay 25 does not at once drop due to the fact that it is also made sli htly slow-releasing and thus the circuit to the top winding of relay 24 is now open at the back contact of armature 4:2. The release period of relay 2% is such that before 23 again swings back to wards the right, so as to close the circuit to the lower winding of relay 24, the relay 2t drops. lVhile 23 is making towards the left a circuit is closed from'positive terminal B through the front contact of armature 45, lower winding of relay 25, left-hand contact of 23 and to thenegative terminal C to hold relay 25 energized. When 23 swings toward the right, the first named circuit for relay 25 is open at armature a as relay 2 1- is now down and before 23 again swings toward the left relay 25 drops due to the fact that its release period is not suiiicient to span a complete cycle of the contact member 2. Hence both relays 24: and 25 are now down ready to start the cycle all over again as contact member next swings towards the left. It will be seen from the foregoing that during every other sending period (coder contacts 19 and making toward the left) the relay is energized and duringthe alternate sending periods the relay 25 is deenergized. During the sending period that relay 25 is up a circuit 'is closedfor the mod ulator M1 from its right-hand terminal along wire -16, front contact of armature 47 of relay 25, wire 4-8, contacts 13, 17 and 8, wire 49, contact 50 of signaling lrey K, wire 51, generator G and wire 52 to the opposite terminal of the modulator M1. During the sending period that relay 25 is down a cir cuit is closed for the modulator M2 from its right-hand terminal along wire 53, back contact of armature 47'of relay 25 and then over the same circuit above traced for the modulator M1 through the generator G and wire 52 connected also to the left-hand terminal of M2. Thus underboth the releaseand running positions of the bralre valve handle 5 and normal position of signaling key K the impulses of current supplied to the traffic rails through the coils 26 and 27 are alter-- nately-modulated at the frequencies of the modulators M1 and M2 in cyclic order.

In the lap position of the handle 5 the power transmitter PT is connected to the inductor coils 26 and 27 by the same circuit as described for the release and running posi- I tions of handle 5. A circuit for the modulator M1 is now completed from the righthand terminal of M1 through contacts 14,17 and 8, wire 49, contact 50, wire 51, generator G and wire 52 back to the opposite terminal of M1. The result is that each impulse supplied from generator G'to the traffic rails under the lap position of handle 5 is modulated at the frequency ofMl as long-as the signaling key K occupies its normal position.

When handle 5 is moved around to the service position, the output of; the power transmitter PT is disconnected from the coder contacts 19 and 20 and connected directly to the inductor coils 26 and 27 by a circuit including wire 31 from the righttus during the service condition of the engineers brake valve. It will be noted that theoutput circuit forthe power transmitter PT remains the same for the emergency position. of the handle 5 but that no circuit s provided for either modulator M1 or. M2. Thus under the emergency condition of the valve EV non-modulated current is continuously supplied to the trafiic rails. To sum up thus far, the release and running positions of handle 5 of the valve EV are identified by a code of control impulses alternately modulated at the frequencies of modulators M1 and 1 M2. The lap position is identified by a code of control impulses modulated at the frequency of M1, the service position by continuous current modulated at the frequency of M2 and'the emergency position by continuous non-modulated current.

The generator G, power transmitter PT and modulators M1 and M2 may take' any one of a number of different types-among them being the vacuum tube type. As the specific type of these devices forms no part ofmy invention they areshown diagrammatically onlyin order to'simplify the drawings as much as possible.

By depressing the signaling key K code message impulses may be transmittedto the traffic rails under either the release, running or lap position of the handle 5 as long as the master switch MS occupies its normal position. With signaling key K depressed the output of the power transmitter PT is disconnected from the coder contacts 19 and 20 and completed through the dotted line position of the contacts 34 and 39 of key K as will be evident from an inspection of Fig. 1. The above traced circuits for the modulators M1 and M2 under the release, running and lap positions are now held open at the upper position of the contact 50 of the signaling key K and a new circuit'is completed for the modulator M1 which includes the right-hand terminal of M1, wire 46, contact 50 in its lower position, wire 51, generator G and wire 52 to the left-ban d terminal of M1. As long as the signaling key K is in its lower position it will be clear that current modulated at the frequency of M1 is continuously supplied to the traffic rails. By operating the signaling key K for long and short periods in accordance with a prearranged code a code message can be transmitted from the locomotive.

During the interval that the code contact members 19 and 20'swing tothe right the inductor coils 26 and 27 are connected to a receiving circuit leading to a filter F through which current is applied to the input of an amplifier AM. The filter F is tuned to pass carrier current of a frequency of a generator G located in the caboose to be referred to later and to filter out current from other sources of power. The amplifier AM amplifies and demodulates the modulated carrier current applied to its input and supplies the current demodulated to its output. With the master switchMS placed at its normal position the receiving circuit mentioned above can be traced from the outside terminal of the coil 27 along wire 87, contacts 7, 16 and 11 with the handle 5 in the release, running or lap position, wire 38, contact 39, right-hand contact of 20, contactor 54: of switch MS. filter F, a second contactor 55 of. switch MS, right-hand contact of 19, contact 34, wire 35, contacts 9, 4; and 6 and wire 36 to the outside terminal of the coil 26. The filter F is connected to the input of the amplifier AM through the contactors 56 and 57 of the switch MS in the No. 1 position as will be easily traced in Fig. 1. The output of the amplifier AM includes the network of two sharply tuned circuits 58 and 59 which can be traced from the right-hand terminal of AM through wire 60, circuit network 58 and 59, wire 61, contactor 62 and to the left-hand terminal of the amplifier AM. The filter F and the amplifier AM'may be any one of many well-known types and as their specific types constitute no part of my invention they are also shown diagrammatically in order to simplify the drawings. A portion of the circuit 58 is connected to the input terminals of a full-wave rectifier 63 whose output terminals are conlator M1 in the caboose is applied to the input of the amplifier AM, the relay 64 is energized and when the modulation is that of M2, the relay 66 is energized. With the mod ulated current periodically interrupted the primary relays 64 and 65 will be operated in step with the impulses in accordance with the modulating frequency.

The caboose equipment, as shown in Fig.

2, includes a generator G, power transmitter PT, a master switch MS and modulators 9 M1 and M2 all of which may be and preferably are similar to the respective devices on the locomotive.

67 and 68 are inductor coils similar to the mounted on the caboose in inductive relation with the traflic rails 28 and 29. These inductor coils at the caboose are connected to either a receiving circuit or to a transmitting circuit in the following manner. With the apparatus of Fig. 2 all deenergized the coils 67 and 68 are connected to the input side of a filter F by the receiving circuit that includes wire 7 0 leading from the left-hand ter switch MS, wire 7 2, back contact of armature 73 of a relay 7 4 to be described later, wire 7 5, coils 67 and 68 in series, wire 76, back contact of armature 77 of relay 74, wire 78, contactor 79 and to the right-hand terminalof filter F. Under conditions to be pointed out later this receiving circuit is completed at times from wire 72 through the front contact of armature 80 of a relay 81 to wire 75 thence through coils 67 and 68,wire 76 and the front contact of armature 82 of relay 81 to the wire 78. As the filter F is normally connected to the input of the amplifier AM through the contactors 83 and 84 of switch MS,current impulses picked up by the coils 67 and 68 will be applied to the amplifier AM. The filter F is tuned to pass current at the frequency of the generator G on the locomotive and to filter out current coils 26 and 27, and these coils 67 and 68 are 2100 terminal of filter F, contactor 71 of the mas- 5110 from other sources. The amplifier of Fig. 2 is preferably similar to that of Fig. 1 and amplifies and demodulates thecarrier current impulses applied to its input. The output of the amplifier .AM includes two sharply tuned circuits and '86 to. which the amplifier is normally connected through the contactor 87 ofthe master switch MS as will be readily understood from Fig. 2. A portion of the tuned circuit 85 is connected to the winding of a relay 88 through a fullwave rectifier 89. In like manner a portion of the tuned circuit 86 is connected to a relay through the rectifier 91. As the circuits 85 and 86 are tunedtoresonance at the frequency of the modulators M1 and M2 .on the locomotive respectively, it follows that relay 88 will be energized when the current is modulated by M1 on the locomotive and the relay 90 energized when the current is modulated by M2 on the locomotive. hen the modulated current is periodically interrupted the relays 88 and 90 will be operated instep with the impulses according to the modulation and when the current is nonmodulated both relays will be deenergized.

Associated with the primary relays 88 and 90 are the direct current polarized relay 92 and the neutral relay 81. When relay 88 is picked up, current flows from the positive terminal B of a direct current source not shown through the winding of relay 81, top winding of relay 92, front contact of armature 93 of relay 88 and to the negative terminal C of the source of current. When relay 9() is picked up, current flows from the positive terminal B through the winding of the relay 81, bottom winding of relay 92 and the front contact of armature 94 to the negative terminal C. While in either case the relay 81 will be energized, the magnetic field created by the energizing of the top'winding of the polarized relay 92 is such as to cause the polarized armatures 95 and 96 to occupy the left-hand position,- thatis the position opposite that shown in Fig.2. The magnetic field created by the energizing of the bottom winding of relay 92 is such as to cause the armatures 95 and 96 to occupy the right-hand position. The polarized relay 92 is so constructed that when it becomes deenergized, its .armatures remain in the position to which they were last moved. From what has just been said it will be seen that when the pri-. mary relay 88 is operated in response to impulses of modulated current, the relay 81 is also operated in step with the impulses and the polarized armatures 95 and 96 of the relav 9.2 are held in the left-hand position. With the primary relay 90 operated, the relay 81 is also operated and thepolarized armatures of relay 92 are continuously held in the right-hand position.

When relay 81 is picked up, current flows from positive terminal B through thewinding of the relay 74 and the front contact of v the armature 97 to the negative terminal C of the current source to energize relay T4. As previously pointed out, the receiving circuit is I completed through the back contacts of armatures 73 and 77 of relay 7 4; or through the front contacts of the armatures 80 and 82 of relay 81, and thus with relay 81 energized in responseto the picking up of either primary relay 88 or 90 the receiving circuit is held closed as long as the impulse lasts. At

the termination of theincoming impulse the relay '81 immediately drops but the relay 7 4: will remain energized for a period as it is provided with slow-release characteristics. During therelease period of relay 74: the in ductor coils '67 and 68 are connected to the output of the power transmitter PT by a circuit from the upper terminal of PT through contactor 98, front contact of armature 99 of relay 74, back contact of armature 82 of relay 81, wire 76, coils 68 and 67, wire 75, back contact of armature 80, front Contact of armature 100, contactor 101 and to the lower terminal of the power transmitter. At the end of the release period of relay 74 armatures 73 and 77 drop to again close the receiving circuit. It follows that the coils 67 and 68 are alternatelyconnected to thereceiving circuit and to the output circuit in step with the action of the relays 81 and 74. The receiving circuit is held closed at all times except for a period immediately fol: lowing the receipt of an impulse when the output circuit is closed for a period equal to therelease period of the slow-release relay 74;.

With the relay 74 periodically energized and deenergized in response to periodic impulses of current received from the traffic rails its armature 102 alternatelyengages front and back contacts. and current flows from the positive terminal of the'source of power alternately through the right and lefthand halves of theprimary winding 1030f a transformer T-.. The low voltage alternating current thus induced in the secondary 104 of the transformer T is applied to the winding of a slow-release relay 105 through a The caboose, of course, will also be equipped with a compressor and all other apparatus to insure ample supplyof air pressurefin the main reservoir MR independent of the usual supply of air pressure on the locomotive.

The valves D and D are each biased to a closed postion and each is lifted to an open position when the associated magnets 107 and 108, respectively, are energized. The valve l) is biased to an open position and is held closed when its magnet 109 is energized. WVhen the valve D is open, brake pipe BP is Connected to the feed valve FV and the auXiliary brake control mechanism reproduces the running condition of the brake valve EV on the locomotive. I When the valve D is open,

' the brake pipe BP is connected to the atmosphere throughfa vent of such characteristics as to produce a reduction of brake pipe pressure: at substantially the service rate of reduction of theusual brake valve to effect a service application of the brakes. When the valve D is open, that'is, when its magnet 109 is deenergized, the brake pipe is connected to the atmosphere through a vent of such characteristics as to produce the emergency rate of reduction of the brake pipe pressure and an emergency application of the brakes. When the valve D is held closed by its magnet being energized and at the same time both valves D and D? are closed both the supply and the exhaust'of the brake pipe are blanked and the auxiliary mechanism reproduces the lap condition of; the engineers brake valve. In the form of the apparatus shown invFig. 2

the magnet for the emergency valve D is the one normally retained energized to insure a closed circuit principle for the equipment. It will be understood, however, that the mag net of either oneof the other valves might be used in this-manner should it seem desirable to do so.- y 1 With relay 105 energized current flows from the positive terminalB of the source of current in the caboose through the winding of magnet l09 and then through the front contact of armature 110 ofrelay 105 tothe a negative terminal C of the current source.

The circuit for the magnet 109 canv also, be

completed throughthe front contact of armature 111 of relay 74. It follows that magnet 109 will. be energized tohold the emergency valve D closed whenever periodic impulses left current flows from the positive terminal B through the front contact 116, operated by the moving partfof'valve D wire 117, left-hand contact of polarized armature 96, winding of relay 112 and to the negative ter- Leo 1,04%

m'inal C of the current source to energize relay 112. As armatures 95' and 96 next swing toward the right, current'flows' as be fore tothe wire 117 thence through the'righthand contactof armature 96 to the winding of relay 113 and to the negative terminal C to energize relay 113. A path is also completed from the right-hand contact of arma ture 95through the front contact of armas ture 118 of relay 112 which relay remains energized due to its slow-release characteristics, top Winding'of relay 114 and to the negative terminal C to energize relay 114'. As armatures 95 and 96 next make toward the left, a path is completed from the lefthand contact of through the front contact of armature 119 of relaylli'l, which remains energized due to its slow-release characteristics, to the top winding of relay-115' and to the negative terminal C to energize relay 115. Relays114 and 115 being also slightly slow-releasing allfour of the relays are now energized and a stick circuit is completed for therelays114 and 115which branches from the wire 117 through the lower windings of relays 115 and'114 in series and'the front contacts of thearmatures 120, 121', 122 and 123 in series and to the negative terminal C. From the foregoing it is evident that relays 114 and 115 will remain picked up as long as the armatures 95 and 96 are periodically swungbetween the two'contacts to energize the slow-release relays 112 and 113. That is to say, these relays 112, 113, 114 and 115 remain energized as long as code impulses alternately modulated at the frequency of M1 and M2 are received at the caboose in response to the running condition of brake valve EV. 1

With relays 114 and 115 picked up the magnet 107 of the valve D is supplied with current from positive terminal B through the ma net 107, b ack contact 124 operated by the valve D front contacts of armatures 125 and 126'of relays 115 and 114,respectively, and to the; negative terminal C. It follows, therefore, that the caboose apparatus so responds to the control code transmitted by the locomotive apparatus under the release or running condition of the brake valve EV as to cause the auxiliary brake controlling mechanism to reproduce the running condition of thejengineers brake valve. I i

The caboose generator G is normally connected to'the input of the power transmitter'PT through the contactor 69 of the master switchMS in the N0. 1 position, as-will be readily seen. from Fig. 2. The current supplied by the caboose generator G is normally modulated at the frequency of the caboose modulator M2 by .means of a circuit that includes the contact 127 of a manually operated signaling key K1, generator G, a front contact ID which is operated from the moving part of the emergency valve D and adapted to be closed when the valve D is closed, andthence back to the other terminal of M2. It was previously pointed out that the output of the power transmitter PT on the caboose is connected to the coils 67 and 68 during the release period of the relay 74 following the receipt of an impulse. It is to be seen, therefore, that the caboose apparatus supplies to the trafiic rails an impulse from the generator G modulated at the frequency of M2 for an interval equal to the release period of relay 7 1 immediate ly following the receipt of an impulse at the caboose. It was previously described that the input circuit on the locomotive is closed each time the contact members 19 and 20 of the coder N make toward the right and that the primary relay 66is energized in response to an impulse applied. to this input circuit modulated at the frequency of M2 in the caboose. It follows that the normal return impulse from the caboose will cause the primary relay 66 to be operated. When relay 66 picked up, current flows iromthe positive terminal B through Winding of a slowrelease relay 128, lower winding of a polarized relay 129, front contact or" armature 130 of relay 66 and to the negative terminal C. With relay 128 picked up to close the front contact of its armature 132 current is supplied to the indicating device 131 which may be a light or a magnet. The polarity of the magnetic field created by energizing the lowerwinding of relay 129 is such as to hold the polarized armature 134m the righthand position. Thus the indicating device 131 is illuminated in response to the normal return impulse received on the locomotive from the caboose apparatus.

Should the locomotive operator select the lap condition for his brake valve EV and cause thereby the locomotive apparatus to send out impulses each modulated at the frequency of M1, the primary relay 88 in the caboose only is operated. Operating relay 88 only causes the polarized relay 92 to hold its armatures in the left-hand position while the relays 81 and 74 function in the same i manner as described for the release'and runniin-g conditions. The relay 113 now being left without energy will become deenergized to open the stick circuit to the relays 114 and 115 and these relaysdrop to open in turn the circuit to the magnet 107 of valve D Magnet 109 remains energized, however, to hold the valve D closed asthe relay 105 is retained energized by the operation'oit relay 74:. As all three -valves D and D are now closed, the auxiliary mechanism reproduces the lap condition established on the locomotive and the return impulses sent out from the caboose are the same as under the running position with the result that the indicating device 131 the valve EV, non-modulated current is supto thelocomotive operator the operating condition of the auxiliary mechanism.

When the locomotive operator moves his valve handle 5 around to the service position and causes current modulated at the frequency of M2 to be continuously supplied to the trafic rails, the primary relay 90 in the caboose is held energized. The relays 81 and 74 are not now operated but are held steadily energized and the polarized armatures of relay 92 remain steadily in the right-hand position. With relay 74 held steadily energized the magnet 109 for valve D is supplied with current by the circuit that includes the armature 111 so that that valve remains'closed although the relay 105 has now become deenergiz-ed. A circuit is completed from positive' terminal B through contact 116, wire 117, right-hand contact of armature 95, wire 135, front contact of armature 136 of relay 74, back contact of armature 137 of relay 105, magnet 108 and'to the negative terminal C to-open the'valve D With valve D open the auxiliary mechanism reproduces the service application condition o1 the brakes established for the engineers brake valve on the locomotive. The continuous energizing of the relay 74 stopsthe sending of return im-' pulses from the caboose as the output circuit is held openat the armatures 73 and 77 with the result that the relay 128 on the locomotive becomes deenergized and the indicating device 131 extinguished.

If the emergency position is selected for plied by the generator G on the locomotive and both primary relays 88 and 90 in the caboose remain deenergized and in turn relays 81 and-7i are deenergized. The magnet 11109 is now without energy and the valve ID is opened to establish an emergency brake application at the caboose.

To sum up the operation of the automatic brake control, the release and running conditions of the engineers brake valve EV cause the locomotive apparatus to alternately assume a sending and a. receiving condition. During the sending condition impulses of "a current of a predetermined frequency are alternately modulated at the frequency of the modulators M1 and M2 and supplied tothe trailic rails through the medium of the inductor coils. During the receiving condition the inductor coils areconnected 'toa :filter through which current is passed to an amplifier. The impulses sent out by the locomotive appara tus are picked up at the caboose and applied to a. receiving circuit that includes a filter tuned to pass current of the frequency of the generator or the locomotive only. The impulses are then amplified and demodulatedto operate primary relays responsive to the mod ulation frequencies of M1 and M2, respeciii-0 tively. The alternate operation of the :pri-

mary relays causes theauxiliary brake controlling mechanism to establish a running condition of the brake pipe pressure and the functioning of a synchronizing means. At the end of each impulse the synchromzmg aeans transfers the caboose apparatus to a sending condition and a return impulse 1s supplied to the traffic rails that has a predetermined frequency and which is modulated at a predetermined modulating frequency. The return impulse is picked up at the locomotive during the receiving condition of its apparatus and applied through its filter to an amplifier which amplifies and demodulates the current to operate a primary relay made motive are all modulated by a single modulator. These lap code impulses picked up at the caboose cause the operation of a single primary relay that in turn causes the auxiliary brake controlling mechanism to establish a lap condition of the brake pipe pressure and the functioning of the synchronizing means. The return indication impulses are the same as sent out during the running condition so that the indicating device is actuated to inform the locomotive operator of the functioning of the auxiliary brake mechanism. The service condition of the brake valve EV causes a continuous impulse of modulated current to be supplied to the traffic rails at the locomotive. The receipt of this continuous impulse at the caboose causes the auxiliary brake mechanism to establish the 7 service brake application condition and holds the synchronizing means in abeyance so that no return impulses are now supplied by the caboose apparatus. The extinguishing of the indicating device on the locomotive indicates to the locomotive operator that the auxiliary brake mechanism has established a brake applying condition. Under the e1nergency condition of the engineers brake valve EV the current supplied by the locomotive apparatus is non-modulated with the result that the caboose apparatus is deenergized and an emergency brake condition established by the auxiliary brake mechanism. No return indication impulses are sent out from the caboose under the emergency condition.

If the locomotive operator desires to send a cod-emessage. he can do so under either the release, running or lap condition by depressing the signaling key K. It has already been described how the depressing of the key K closes the output circuit around the contact members 19 and 20 and completes a circuit for the modulator M1. The duration of the current impulses supplied to the trafiic rails is now determined by the manner in which the key K is operated. The impulses may be made long or short by holding the key K down for long or short intervals. It should be noted, however, that these code message impulses all should be at least longer than the normal impulses supplied under the automatic brake control condition. The code message impulses being modulated by M1 will be received at the caboose by the operation of the relay 88 for periods corresponding to the long. and short periods of operating the key K. Each time relay 88 is picked up, relays 81 and 7 4 are held energized for the entire period and the polarized relay 92 is held in the left-hand position. Helay becomes deenergized during the code message impulses and completes a circuit to the signal light L from positive terminal B through contact 116, wire 117, left-hand contactof armature 95, back contact of armature 138 of relay 105 and signal light L to the negative terminal C. Signal light L thus illuminated displays to the caboose op erator the code message established by the locomotive operator operating the key K. With relay 92 held in the left-hand position during the period of a code message the relay 113 would become deenergized to trip off the relays 114 and which would cause brake valve D to become closed. To guard against such operation of valve D during the sending of a code message the relay 113 is provided with an extra circuit by which it is supplied with current from positive terminal B through contact 116, wire 117, back contact of armature 139 of relay 105 as that relay is now deenergized, wire 140, winding of relay 113 and to the negative terminal G. lVith relay 113 thus energized and relay 112 retained energized due to armature 96 being held in its left-hand position the valve D is retained open during the sending of a message under the release or running condition of the brake valve EV. In connection with this it should be noted that the release period of relay 105 should be made slightly shorter than the release period of the relay 113. The 1 sending of a message during the lap position of the handle 5 will not cause valve D to be opened in response to the energizing of the relay 113 by this extra circuit just traced as the relay 114 is now down due to the fact that it is deprived of current at the right-hand contact of armature 95 and as the stick circuit for relays 114 and 115 was opened when the lap condition was first established in response to the lap code.

To send a code message from the caboose the caboose operator depresses the signaling key K1 causing thereby contact 127 to occupy its dotted line position so that the return impulses are modulated at the frequency of M1 instead of at the frequency of M2 as will be evident by inspection of Fig. 2. The receipt of an indication impulse modulated at the frequency of M1 causes the primary relay 64 to respond and complete at the front contact of its armatur 143 a circuitfor re lay 128 through the top winding of the relay 129. ,VVhile relay 128 is retainedenergized to actuate the indicating device 131 in the usual manner, the magnetic field created by the energizing or" the top winding of the relay 129 is such as to cause its armature 134 to be reversed to the left-hand position where'it closes a circuit to the signaling device 141, It follows that actuating the signaling key K1 causes both the indicating device 131 and the signaling device 141 to be displayed on the locomotive. By operating the key'Kl according to a prearranged code a code message can be transmitted from the caboose tothe locomotive operator.

As stated above, thefNo. 2 and the No. 3 positions of the master switches MSare used for telephone communication. It the locoi motive operator wishes to talk with the caboose crew, he depresses his signaling key K for a long period and then returns it to its normal position. i This long code impulse causes the signal L in the caboose to be displayed indicating to the caboose operator that telephone communication is desired. The aboose operator places his master switch .MS in its No. 3 position and as the return indication impulses are now discontinued, the

' locomotive operator knows by the extinguishing of light 131 that the caboose apparatus is ready to receive his message. As the master switch MS in the cabooseis moved to the No. 3 position, its receiving circuit is disconnected from the filter F and connected directly to the input of the caboose ampli fier AM. This input circuit can be traced from the upper left-hand terminal of amplifier AM to contactor'79 in No. 3'position,

wires liand 7 6, coils 68 and 67, wires 75 and ill, contactor 83 in No. 3 position and to the upper right-hand terminal of AM. The output otthe amplifier AM is at the same time switched from the circuit network to the loud speaker LS by the contactor 87 in the No. 3 position. The operator on the locomotive now moves his master switch MS to its No. 2 position. The moving of the contactor of switch MS from the No. 1 to the No. 2 position disconnects the generator G from the power transmitter PT and closes a circuit for a speech transmitter ST in its place. The output of tie power transmitter PT is now connected directly to the inductor coils 26 and 27 y the contactors 32 and 41 being moved to the No, 2 position as will be easily traced in Fig. l.- lt will be noted that the circuits for too filter F and the amplifier AM on the locomotive are opened when switch MS is moved to its No. 2 position. The speech transmitter ST and the loud speaker LS may be onefof many types used in this class of work and, as their specific typeforms no part ofmyinvention, they are shown diagrammatically only. Through the medium .ofthe speech transmitter ST and power transmitter PT the locomotive operator supplies to the tralfic rai s his spoken message in the form of a carrier current modulated at voice. frequencies which when picked up at the caboose and applied to the amplifier AM is demodulated andreproduced by the loud speaker LS. To get an answer back the locomotive operator moves his switchMS to its No.3 position where the inductor coils26 and 27 are connected directly to the input of the amplifier AM bya circuit that includes the contactor in the No. 3 position, wire 37 coils 27 and 26, wire 36 and contactor 56 in the No. 3 position back to the amplifier AM. The output of'theamplifier AM on the locomotive is now switched to the power transmitter in place of the ge1i-y orator G by the contactor 69 and where the output circuit for the power transmitter PT is connected directly to the coils 67 and 68 by the contactors .98and 101. Through the me-, dium of his speech transmitter and the power transmitter the spoken message at the ca:

boose is supplied to the traffic rails which is picked'up at the locomotive, amplified, demodulated and reproduced by the loud speaker LS. At the end of the telephone conversation both operators will return their master switches to the normal position, causing the exchange of control impulses to be resumed.

To prevent the auxiliary brake controlling mechanism from going to a brake applying condition during telephone communication under the running condition of the mechanism extra circuits are provided which are completed whenever the master switch MS is shifted to either the No. 2 or No. 3 position.

The extra circuit supplies current from the positive terminal 13 throu h winding of relay 81, top winding of relay 92 and contactor 71 to the negative terminal C. With relay 81 energized the relay 74 is picked up and the magnet 109 of the emergency valve D retained energized by the circuit through front contact of armature 111 as previously pointed out. A second extra circuit includes positive terminal B,'contact l16, wire 117, contactor 84, winding of relay 113 and the negative terminal C. As relay 112 is held energized due to the fact that polarized armature 96 is held in theleft-hand position by the first extra circuit and with relay 113 energized by the second extra circuit, the relays 114C and 115 are retained energized and current supsage. The procedure from this point on is plied to the magnet 107 to hold open the valve D If it is the caboose operator who wishes to establish telephone communication, he initiates-communication by first depressing his signaling key K1 and then holds it there until the control impulses cease to be receivedatthe caboose, which will be indicated to him by'the extinguishing of the signallight L due to the fact that relay 105 becomes deenergized as the control impulses cease and thereby opens the normally closed circuit for L at the front contact of the armature 142. He then knows that the locomotive operator has put his master switch in the No. 3 position ready to receive his telephone message. The caboose operator now restores the signaling key K1 to its normal position and places his master switch MS in its No. 2 position and delivers his mesthe same as described above fortelephoning from the locomotive. As the output of the.

power transmitted PT on the caboose is held open during service and emergency brake conditions at'the' contacts of relays 74 and 81, no telephone conversation can be established under these brake applying conditions. If it should become necessary to initi ate a brake application during a conversation, the locomotive operator would indicate the same by saying brakes or some other word agreed upon, after which both operators would release their master switches and let the brakes apply automatically at the caboose according to the condition-established at the locomotive.

In the form of my invention disclosed in Figs. 3 and 4 the brakes are to be controlled at each end of the train under t ,.e direction of telephonic messages transmitted between the locomotive and the caboose. To'insure thatcommunication between the operators at the two locations can be established at any and all times check impulses of current of audible frequency are periodically exchanged automatically, under normal conditions, be tween thetwo. locations to check the operativeness of the communicating channel. These check impulses produce at each end of the train an audible note or signal by which the operators are kept informed of the operativeness of the communicating channel and the normal condition of the apparatus. The manually operated circuit controllers or master switches -MS at each location permit the operators to discontinue the automatic exchange of impulses and establish telephone conversation. Thus, they can then exchange spoken information that will enable them to manually set up corresponding conditions of the air brakes substantially simultaneous. 1y, or govern the brakes in a manner as may seem best for proper handling of the train.

The equipment ZitiGaClLEHC l of the train has three distinct operating conditions, as follows: first, a normal condition during which the check impulses are exchanged between the locomotive and the caboose, or as at times current of audible frequency is continuously transmitted from the locomotive; second, speech sending condition during which spoken messages can besent to the operator at the other location; third, speech receiving condition during which spoken messages can be received from the operator at the other location.

Referring to Fig. 3, the locomotive is provided with a generator G, power transmitter PT, speech transmitter ST, filter F, amplifier AM, loud speakerLS, master switch MS and a coder N similar to the respective devices described in reference to the locomotive equipment of Fig. 1, eizcept for the fact that the amplifier AMv does not demodulate the current before it is supplied to the output and the speech transmitter ST delivers current of voice frequencies only. Under the release, running and lap positions of handle 5 of the brake valve EV, when master switch MS is normal, the power transmitter PT amplifies the current supplied by the generator G and delivers it to the inductor coils 26 and 27 by atransmitting circuit which in this instance includes the top terminal of PT, contactor 32 of the master switch MS, wire 33, left-hand contact of the contact member 19 of coder N, wire 145, contacts 9, 4 and 6, wire 36, coils 26 and 27, wire 37, contacts 7, 16 and 11, wire 146, left-hand contact of 20, wire 147, contactor 41 and the lower terminal of the power transmitter PT. As the contact members 19 and 20 of coder N swing to the right, the inductor coils 26 and 27 are shifted to a receiving circuit leading to the filter F through which current is passed to the amplier AM. To be specific, this receiving circuit extends from the right-hand terminal of filter F, contactor 55, right-hand contact of 19, wire 145, contacts 9, 4 and 6, wire 36, coils 26 and 27, wire 37, contacts 7,

16 and 11, wire 146, right-hand contact of I 20, and contactor 56 to the left-hand terminal of the filter F. The filter F is connected to the input of amplifier AM through the contactors 57 and 62 while the loud speaker LS is permanently connected to the output of amplifier AM. Thus, with the master switch MS normal and the brake valve handle 5 in either the release, running or lap position the contact members 19 and 20 when making towards the left close the output cir cuit and an impulse of current from the gen erator G is supplied to the trafic rails. Each time contact members 19 and 20 make toward the right the coils 26 and 27 are connected to the filter F. The filter F is tuned sharply to the frequency of the current delivered by agenerator in the caboose making it possible to selectively receive impulses transmitted from the second location on the same train and at the same time exclude impulses of a different frequency from some other nearby train.

In the event handle 5 is moved around to either the service or emergency position the output of the power transmitter PT is connected to the inductor coils by a circuit that includes only contacts of the contact assembly associated with the valve EV ascan be readily traced from Fig. 3. It follows that under the service and emergency positions of handle 5 current from the generator Gris continuously supplied to the traffic rails as long as the master switch MS is normal. It is to I be noted that under the service and emergency positions the receiving circuit from the inductor coils to the filter F is held open.

Whenthe master switch MS is moved to its No. 2 position, the above traced receiving Circuit to the filter F is held open at the contactors 55 and 56, the generator G is disconnected from the power transmitter PT at contactor 30 and the speech transmitter ST is connected to the power transmitter atthe contactor 54;. At the same time the'output of the power transmitter is connected directly to the inductor coils, as will be evident from an inspection of Fig. 3. Thus, under the No. 2 position of the master switch spoken messages can be supplied to the trafiic rails through the medium of the speech transmitter ST and the power transmitter In the No. 3 position of the master switch MS of Fig. 3 the output circuit of the power transmitter is held open at the contactors 32 and 41 and the input of the amplifier AM is connected directly to the inductor coils 26 and 27 by a circuit that includes the top terminal of AM, contactor 55 in No. 3 position, wires 169 and 36, coils 26 and 27, wires 37 and 170, contactor 56 in No. 3 positionand' the lower terminal of amplifier AM. As the input of amplifier AM is not now selectively tuned by the filter F, energy of the range of voice frequencies picked up by the coils 26 and 27 will be reproduced by the loud speaker LS.

From the foregoing, it is seen that with the normal position of switch MS the output circuit of the power transmitter PT and the input circuit to the filter F are alternately connected to the inductor coils 26 and 27 once each cycle of the coder N as long as the handle 5 is in the release, running or lap position. When the handle 5 is moved to the service or emergency position, the power transmitter is connected continuously to the coils and the current impulse supplied from generator G to the traiiic rails is continuous. When the master switch is shifted to the No. 2 position, the generator G is disconnected from thepower transmitter, and in its place the speech transmitter connected, and the output of the power transmitter reconnected d1- ter switch is shifted to the No. 3 position, the output circuit of the power transmitter is held open and the inductor coils are connected directly to the input of the ampliomitted from the valve E l/ 1 such, for ex ample, as the release condition. The apparatus of Fig. a includes a generator G, power transmitter Pi, speech transmitter ST, filter F, amplifierfilth-loud speaker and a master switch MS similar to the respective devices described in connection with the apparatus of Fig. 3.

.rectly to the inductor coils. lTTh'en the mas- Suppose for the ime being that the equipment of Fl g. l is all deenergized and its masterjswitch MS normal. The 'nductor coils 6'? and 68 are now connected to the input side of the filter F by a circuit that extends from the top terminal of filter F, contactor 79, wire 148, back contact of armature 149 of a relay 150, wire 151, coils 68 and 6'"! in series, wire 152, back Contact of armature 153 of relay 150, wire 15%, contactor, 83 and to the lower terminal of filter F. The output of filter F is connected to the input of the amplifier AM by a circuit easily traced through the contactors S4 and 87 of the master switch MS. The output ofthe amplifier AM is fed to a circuit that extends from the right-hand terminal of Ald through contactor 155, one side of a full-wave rectifier 156, wire 15?, winding of a relay 158, wire 159, other side of rectifier 156, loud speaker LS, contactor 160 and the le t-hand terminal of amplifier AM. i

Filter F in the caboose is selectively tuned to pass only current of the frequency supplied by the generator G on the locomotive. As mentioned above, the filter F on the locomotive is selectively tuned to pass only current of the frequency delivered by the generator G in the caboose. Thus the appa ratus at each end of the train is made selectively responsive to the normal control impulse transmitted by the apparatus at the opposite end of its train and is not responsive to the impulses that may be transmitted from other trains, it being understood that in practicing my invention, it is proposed to assign a distinctfrequency to each train of the railroad.

through the front contact of the armature 163 ofrelay 158. As soon as relay 162 is picked up, current flows from battery 161 to the winding of relay150 by a circuit easily traced through the front contact of armature 16% of relay 162. Vhth the relay 150 energized, the receiving circuit traced above for the filter F is opened at the back contacts of the armatures 149 and 153. This receiving circuit to the filter F is now closed, however, at the front contacts of armatures 165 and 166 of the relay 162 and thus these three relays 158, 162 and 150 will remain energized until the end of the incoming control impulse.

At the end of the impulse, the relay 158 is deenergized and relay 162, in turn, drops. The relay 150 is provided with slow-releasing characteristics and thus it remains energized for its release period after the relay 162 drops to open the circuit to the Winding of relay 150. During the period in which relay 150 is up and relay 162 down, a transmitting circuit is closed from the output side of the power transmitter PT through the contactor 98 of switch MS, front contact of armature 167 of relay 150, back contact of armature 165 of relay 162, wire 151, coils 68 and 67, wire 152, back contact of armature 166, front contact of armature 168, contactor 101 and to the other terminal of the power transmitter PT. It is clear that during the release period of relay 150 current is supplied from the generator G to the inductor coils 67 and 68 through the power transmitter PT and a short current impulse is transmitted from the caboose equipment to the traific rails. When relay 150 drops, the transmitting circuit is opened to terminate the sending of the return impulse, and the receiving circuit to the filter F is again closed at the back contacts of the armatures 149 and 153 to place the caboose equipment in condition ready to receive the next short impulse sent out from the locomotive.

As pointed out above, the locomotive apparatus sends out an impulse under the release, running and lap conditions of the valve EV during the period the oscillator N swings the contact members '19 and 20 to the left and then closes its receiving circuit to the filter F during the periodthe contact members 19 and 20 are swung to the right. The control impulse sent out is received at the caboose as its receiving circuit is normally closed'and this impulse when applied to the caboose filter F is passedon to its amplifier AM causing thereby a note to be sounded by its loud speaker LS and the relays 158, 162 and 150 to function as described above. At the end of'the impulse, the caboose apparatus assumes a transmitting condition during the release period of the relay 150 which is made somewhat less than the interval the oscillator N holds the contact members 19 and 20 towards the right. The return impulse supplied to the traflic rails by the caboose equip ment is picked up by the coils 26 and 27 at the locomotive and applied through the filter F to its associatedamplifier AM and thence to the loud speaker LS causing thereby a short note to be sounded on the locomotive. As long as the normal running condition remains in effect short notes will be intermit tently'soun'ded b'othin the caboose and on th'ellocomotive. The sounding of these short notes in the caboose under normal running condition instructsthe caboose operator to hold the brake valve EVl at the running position. The sounding of the notes on the locomotive informs'the operator there that his control impulses are being received at the caboose and that the system is properly functioning.

Should the locomotive operator new place his valve handle 5 at either service or emergency position, where the locomotive trans mitting circuit is continuously held closed,

energy is constantly supplied to thetrafic rails 28 and 29, so that in the caboose, the relays 158, 162 and 150 are all held energized and its loud speaker sounds a continuous note. A steady sounding of the caboose loud speaker is an indication to the operator there that heshould make an application on the brakes by his brake valve EVl. 7

After a bral-te application has been made ralze valve handle 5 to the lap, running'or closes-position, a short note will again he so'undeo intermittently in the caboose. The operator in the caboose will not know whethe to place his brake valve at lap or in the runposition. It is therefore necessary that he put his brake valve in the lap position and obtain instructions by telephone from the operator on the locomotive as to what conditi on he is to set up.

' It has already been pointed out that when the master switch M8 on the locomotive is moved to its'llo. 2 position, the generator G is disconnected, the circuit for the speech transmitter closed and the output of the power transmitter PT connected directly to the inductor coi 26 and JV hen the master switch MS in the caboose is shiftedto its No. 3 position, the inductor coils 67 and 68 are connected directly to the input of the amplind the locomotive operator has returned his conversation fier by a circuit which includes the contactors 83 and 84 in position 3 as can be easily traced from Fig. 4. Also the contactors and of the master switch in the caboose connect the loud speaker LS directly to .the output of the amplifier AM in the Nb. 3 position.

Thus, as the locomotive operator terminates a brake application and the caboose operator laps his brake valve, the caboose operator will shift his switch MS to its No. 3 position, and the operator on the locomotive will shift his switch MS to its No. 2 position, after which the locomotive operator will issue verbal instructions through his speech transmitter ST that will be reproduced by the loud speaker LS in the caboose instructing the caboose operator as to how. he shall operate his brake valve.

In the event the locomotive operator desires to talk to the caboose operator during the normal running condition, he will shift his switch MS to its No. 3 position and place his apparatus in speechreceiving position, causing thereby the normal check impulses to cease. On the caboose no note will be sounded and the caboose crew will know that the operator on the locomotivewishes to talk to them. The caboose operator will then shift his switch MS to its No. 2 position where his speech transmitter ST is connected to the power transmitter PT by the contactor 7 1, and inform the locomotive operator verbally that he is ready to receive his message, after which he immediately shifts his switches to the No. 3 position. The locomotive operator will now shift his switch toits No. 2 position and convey his message by means of his speech transmitter ST. By operating their switches between the speech receiving and speech transmitting positions, the two operators can carry on any conversation necessary to properly control the train.

If the operator in the caboose wants to speak to the locomotive'operator, the procedure is similar to that described above. The caboose operator first shifts his master switch MS to its No. 3 position causing thereby the check impulses, to cease. The locomotive operator shifts his switch MS to its No. 2 position and informs the caboose operator that he is ready to carry on a telephone At the end of a telephone conversation both operators will allow their master switches to return to the normal posi tion and the exchange of normal check impulses Willthen be resumed. Ifduring a conversation an emergency should arise that makes it necessary for the locomotive operator to apply the brakes, he can at the same time give orders for a brake application to the operator in the caboose through the telephone conversation, thus avoiding loss of time in stopping .the train.

To sum up the operation of the system as disclosed in Figs. 3and a, the apparatuson each end ofthe train being inthe No. l position, impulses'of current 'of a given frequency are transmitted from the lQcomo: tive to the caboose, which when applied to an amplifier, through a' filter sharply tuned to the given frequency of the current pro,- 1

duce a note fromthe' loud speaker, and also cause a'group of relays to so function that the caboose apparatus is shifted from receiving to sending condition in step with the oscillations of the ocillator N onthe locomotive. During the sending period at the caboose, an impulseof audible frequency current is -trans-' mitted to the locomotive which when applied to its amplifier through a sharply tuned filter produces a short note at the loud speaker on the locomotive. When the operator on the locomotive moves his brake handle to a brake applying position, the transmitting circuit on the locomotive is continuously held closed so that current is continuouslytransmitted from the locomotive to the caboose to produce a steady sound of the caboose loud speaker indicating to the caboose operator that heis to make a brake application. By shifting the master switches to speech sending and speech receiving conditions, a speech transmitter is substituted for the generator and the sharply tuned filter is eliminated so that the ampliher is broadly responsive to frequencies of the voice range, and conversation can be carried on betweenthe two operators.

Control systemslsuch as here disclosedare highly selective-as to the normal current impulses thereby insuring against interference from nearby control systems. A single C01 1- munication channel serves for the normal automatic control and is available for telephone communication at the option of the operators. As stated earlier in the specification, my invention is not limited to control systems for railway trains alone butis adaptable to other locations where mechanisms spaced apartare interrelated in their operating conditions. The forms here shown for my invention Will serveto illustrate a manner by which 1 propose tocombine an automatic control system i and a telephone communicating system between two locations with a singlecommunieating channelserving both.

Although I have herein shown and described only certain forms of apparatus embodying my 1nvention,.1t s understood that various changes and modifications, may be made therein within the scope of the append ed claims without departing from thespirit and scope of my invention.

Having thus described my invention, what I claim is: V7 H 1. A' control system including, atransmiting circuit a source of control current of a iii predetermined frequency, coding means adapted to supply to said circuit from said source periodic impulses of current, telephone means adapted to supply to the transmitting circuit a telephone current of voice frequencies, a receiving circuit influenced by said transmitting circuit, means controlled by said receiving circuit responsive only to current of the predetermined frequency of the control current to establish a signal corresponding to the periodic impulses, and other means controlled by the receiving circuit responsive to the telephone current to establish telephone communication.

2. A control-system including, a transmitting circuit, a control means adapted to sup "ply to the transmitting circuit a control current of a predetermined frequency, telephone means adapted to supply to the transmitting circuita carrier current modulated at voice frequencies, a receiving circuit influenced by the transmitting circuit, filtering means controlled by the receiving circuit responsive only to current of the predetermined frequency of the control current to establish a signal, demodulating means controlled by the receiving circuit responsive to the voice frequencies to establish telephone communication, a manually controlled means associated Witlithe transmitting circuit to render either the control means orthe telephone means active, and Y a second manually controlled means associated with the receiving circuit to render either the filtering means or the de modulating means responsive.

8. A control'systemincluding, a transmitting circuit having a control condition and a telephone condition, a source of current adapted to supply current of a predetermined frequency to said transmitting circuit under the control condition, speech transmitting means adapted to supply a current modulated at voice frequencies to said transmitting circuit under the telephone condition, a first receiving means including a filter responsive only to current of the predetermined frequency to establish a control, a second receiving means including a demodulator responsive to the voice frequencies to es tablish telephone communication, and manually controlled means to selecteither the control condition or the telephone condition of the transmitting circuit and to render either the first or the second receiving means responsive.

4. A control system including, a transmitting circuit, a current source adapted to supply to said circuit control current, coding,

means to code said control current and to selectively modulate the code impulse with any 7 one of a, plurality of frequencies in accordance with difierent operating conditions, telephoning means adapted to supply to the transmitting circuit current modulated at voice frequencies, a receiving circuit influenced by said transmitting circuit, means controlled by said receiving circuit resporr' sive to said code impulses and said voice frequencies to selectively establish an operating condition corresponding to the modulating frequency of the code impulses and to establish telephone communication, and manual ly controlled means to selectively render either the coding means or the telephoning means active.

5. A control system including, a transmitting circuit, a current source adapted to supply to said transmitting circuit a control current of a predetermined frequency, coding means to code said control current and to selectively modulate the code impulses With any one of a plurality of frequencies in ac cordance with dii erent operating conditions, a speech transmitter adapted to supply to the transmitting circuit current modulated at voice frequencies, a first receiving means responsive only to current of the predetermined frequency of the control current to selectively establish an operating condition corresponding to the modulating frequency of the code impulses, a second receiving means responsive to the voice frequencies to establish telephone communication, and manually controlled means to select either the control current source or the speech transmitter and to render either the first or the second receiving means responsive.

6. A control system including, two spaced locations, a communicating channel between said locations, a transmitting and a receiving means at each location arranged to normally exchange automatically periodic impulses of current between said locations through said communicating channel to render active a sig naling device at each location, a first manually controlled means at each location each adapted when actuated to render the transmitting and receiving means ineffective to exchange said periodic impulses of current but active to exchange code message impulses, and a second manually controlled means at each location each adapted when actuated to render the transmitting and receiving means ineffe'ctive to exchange either'the said periodic impulses or said code message impulses but active to eXchang-e'telephone conversations between said locations through said comniunieating channel.

7. A control system including, two spaced locations, a communicating channel between said locations, an operating mechanism at one location having a plurality of operating conditions, a first manually controlled means at the other location adapted to supply to the communicating channel a plurality of clifferent codes of current, a receiving means at the first mentioned location influenced by said communicating channel selectively responsive to the different codes to establish a corresponding operating condition of said operating mechanism, a second manually controlled means at said other location adapted to render the first manually controlled means ineffective and to supply code message impulses of current to said channel, means at the first location selectively responsive to said code message impulses to establish a code signal, a third manually controlled means at said other l0cation adapted to render both first and second manually controlled means inefiective and to establish telephone conversation over said channel, and means to retain the operating mechanism in its active condition during the receiving of a code message and during telephone conversation. 1

8. A control system for railwaytrains including, two locations spaced apart on a train, a transmitting circuit including a generator of audible frequency current of a predetermined frequency at each location, a loud speaker at each location, a receiving circuit at each location tuned to respond only to current of the frequency of the generator at the opposite location to control. the loud speaker at the same location, and automatic means at each location to alternately render active the transmitting and receiving circuits and synchronized with the automatic means at the opposite location to thereby auto-l matically exchange telephgonic signals be:- tween the two locations.

9. A control system for railway trains including, two locations spaced apart on a train, amechanism at each location each having an operating condition, a master circuit controlling switch having a normal and a telephone condition at each location, means rendered active under the normal condition of said master switches to automatically exchange between the two locations periodic impulses of current to establish the operating condition of said mechanisms, and means rendered active under he telephone condition of said master switches to permit telephonic messages to be exchanged between said two locations.

10. A. control system for railway trains including, a master train operating mechanism having different operating positions at one location on atrain, an auxiliary mechanism at a second location on the train adapted to reproduce the different positions of the maser mechanism, a circuit controlling switch at each location having a'normal position and a telephone position, circuit means rendered active under the normal positions of said switches for causing the auxiliary mechanism to reproduce the position of the master mechanism, other circuit meansrendered active under the telephone position of said switches to permit telephonic messages to be exchanged between the two locations, and.

means to retain the auxiliary mechanism in its established position during the exchange of telephonic messages.

11. A control system for railway trains including; a mechanism ateach of t-wo'locations on atram each having a train operatmg condition, a code message condition and a telephone condition, said mechanisms adapted to cooperate with each other when in corresponding conditions; and manually controlled means at each. location to select the condition of its mechanism and thereby establish a corresponding train operating conditionfor the train at each location, or to exchange code messages between the two locations, or. to establish. telephone communication between said locations.

12. A control system for railway trains ineluding; a first circuit means adapted to establish any one of. several dilferent operating conditions for the train at each of two different locations on the train, a second circuit means adapted to exchange code messages between said two locations on the train, a third circuit means adapted to permit telephone communication between the two locations, and manually controlled means at each of said locations to select which of said circuit means shall be active. v

13. Apparatus for the control of the brakes of a railway train including, a manually operated brake controlling valve capable of producingdift'erent conditions of the brake pipe pressure, a generator of a predetermined audible frequency current located at another point on the train, a manually controlled transmitting means to selectively cause said generatorto transmit different code impulses of said current corresponding to the different conditions of the brake controlling valve, an electroresponsive means influenced by the transmitting means, and a signaling device controlled by the electroresponsive means adapted to produce an audible note in response to each impulse of the audible frequency current to thereby distinguish the diii 'erentcodes and determine the condition to be established by the opcrator of said brake controlling valve. I

l l. A control system for railway trains in combination with the usual engineers brake valve on the locomotive, an auxiliary brake controlling mechanism at another location on the train capable of reproducing different functions of the engineers brake valve, a first manually'controlled means on the locomotive adapted to supply different codes of current corresponding to different functions of the engineers valve, receiving meansat said other location selectively responsive to said difii-erentcodes of current for causing the auxihary mechanism to register with the engineers valve, a second manually controlled the first and second manual means ineffective and to establish telephone communication etween the locomotive and said other location. 7

15. A control system including, two locations spaced apart; a generator of audible frequency current of a predetermined frequency, a loud speaker, a speech transmitter, a transmitting means and a receiving means located at each location; a master switch for each location adapted to assume different positions, a first circuit means at each location including a filter sharply tuned to pass current of the frequency of the generator at the opposite location rendered active in one position of the master switch to alternately connect said generator and the loud speaker to the transmitting and receiving means and synchronized with said first circuit means at vthe other location to automatically exchange telephonic signals between the two locations, a second circuit means at each location rendered active under a second position of its master switch to connect the speech transmitter only to the transmitting means and thereby transmit from that location a spoken message, and a third circuit means at each location rendered active under a third position of its master switch to connect the loud speaker only to the receiving means to thereby receive a spoken message at that location.

16. In combination, a generator of audible frequency current of a predetermined frequency, a loud speaker, a first circuit means includinga filter tuned to pass current of a given frequency only'to control at'times the loud speaker, anelectroresponsive device capable of either transmitting or receiving energy, a manually operated circuit controlling switch adapted to assume difierent positions, means to alternately connect said generator and said first circuit means to said electroresponsive device under one position of said switch to thereby alternately transmit and receive automatically a telephonic signal, a speech transmitter, a second circuit means to connect said speech transmitter only to said electroresponsive device under a second position of said switch to thereby transmit a spoken message, and a third circuit means to connect the loud speaker only to said electroresponsive device under a third position of said switch to thereby receive a spoken message. 7

In testimony whereof I afiix my signature.

ANDREW J. SOBENSEN. 

